The Stable Microbubble Test for Determining Continuous Positive Airway Pressure (CPAP) Success in Very Preterm Infants Receiving Nasal CPAP from Birth

Abstract

Background: Very preterm infants can be treated with nasal continuous positive airway pressure (CPAP) from birth, but some fail. A rapid test, such as the stable microbubble test (SMT) on gastric aspirate, may identify those who can be managed successfully using CPAP. Objective: To determine if SMT can identify soon after birth, very preterm infants who may be successfully managed on CPAP alone. Methods: Stable microbubbles (diameter <15 µm) were counted in gastric aspirates taken <1 h of age from infants <30 weeks' gestation, who received CPAP from birth. Infants failed CPAP if intubated at <72 h of age. Clinicians were masked to SMT results. A receiver operating characteristic curve was generated to determine the relationship between number of microbubbles/mm² and subsequent intubation. Results: 68 infants of mean (SD) 28.1 (1.4) weeks' gestation received CPAP in the delivery room at a median (interquartile range) pressure 7 (6-8) cmH₂O and FiO₂ 0.25 (0.21-0.3). Gastric aspirates were taken at a median (interquartile range) age of 0.5 (0.3-0.6) hours. The best cut-off point for predicting CPAP success or failure was a SMT count of 8 microbubbles/mm². The area under the receiver operating characteristic curve was 0.8 (95% CI 0.7-0.9). A SMT count ≥8 microbubbles/mm² had a sensitivity of 53%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 60% for predicting CPAP success. Conclusion: Infants treated with CPAP from birth, who hadSMT counts ≥8 microbubbles/mm² on their gastric aspirate, did not fail CPAP.

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